DID NOT UNDERSTAND MOVIE

As funny as it might sound...though I did not understand fully the movie...I truly did enjoy it! I really did! I watched the movie twice from beginning to end...and still...I am confused. Okay...I remember them filming their movie and then mentioning the use of old movies that still had film to be used at the end. Well, when they did just that...they watched THEIR movie as a preview of what they had so far...and instead, the OTHER movie (from the past...that kind of starts it all)...begins playing. I saw that figure behind the main actress and remember the main character guy stating that he remembered seeing the OTHER, unknown movie when he was in the second or third grade and being scared of it. Well, as the movie continues...weird happenings begin to occur. And the younger actress of the movie being filmed is pushed off the catwalk. Well, later on weird things still occur even after the younger actress is dead. So...who is it??? I mean is it the "figure" from the first movie doing all the evil-doings? Or does the younger actress have something to do with it? And then the other new actress who comes to be a stand-in for the young actress who was pushed from the catwalk freaks out and starts laughing like the figure that is pictured behind the actress in the OTHER, old film. But wait...in the article...it is the MAIN actress of the OTHER, old film that is pushed off...not the figure that is behind her. So what the heck is going on here?? Can someone possibly help my confusion? You can email me at [email protected] and just use the heading DID NOT UNDERSTAND MOVIE in the email heading so I know what it is. Really...I loved this movie...but would probably love it even more if I understood it! THANKS!